Channel testing circuit



w. H. T. HOLDEN CHANNEL TESTING CIRCUIT March 16, 1954 2 Sheets-Sheet 1Filed Oct. 17, 1950 k MN OWN INVENTOR -W. H. 7: HOLDEN ATTOBNEV w. H. T.HOLDEN 2,672,521 CHANNEL TESTING CIRCUIT 2 Sheetsl-Shet *2 March 16,1954 Filed Oct. 1'7, 1950 8w 3 vNN WQN wd oom ATTORNEY Patented Mar. 16,1954 2,6725% CHANNEL. TESTING- GtRCUIT' William IL '12 Human; Pasadentt,cam, as'signor to B13111 Telephbne Laboratories; lncoi'pmatedas NewYork, N; E, a: corporation of. New York Animation Oc't'biier. 17, 19st,,Sfrihl' No. 190,42

Claims; 2

This invention relates to automatic telephone systems employing commoncontrol equipment we hesfor its object to'improvethe' testing andselecting" operations of such equipment.

In a telephone system in which connections are completed by means ofcross-mar switches; the selection of the necessary switch elements underthe control of common conttol circuit known as a,- marker. A system ofthe type to'whi'eh the present invention refeit eeis shqw'n inUni'tedStates Patent 2-,235fi6 3-to W. W. 6&1 pen-tel; detedTha-r'ch 18; 194 1. Y

The setting up of a complete connection in such a system takes place intwo stegesf; one cbnne'etm the calling line 13 way of a, district mentortoa trunk and" the other connecting the trunk to the called Iin'e. Thetwo stages" are h-a,nd1ed= by separate markers and may also be s'etup asparts of outgoing" calls of incoming calls.-

Whem ass-marker is called upon w set up one stage of ar conneeti'on itreceives an indication oi the identity ofthe' cireuite to be connectedand connects therewith: It then tests for and selects itile channel byWinch these siren-its may be connected and-'- operatesthe switchesmaking up the channel tocehn'eet the'oircifitsi A channelihclude'scross-points on four SW 'ch'es one the three links connecting theseet'os's-p' 'n-ts. In order to identify an i'dle channet, themarker mustfii 'sttest the thr'ee" Ii 01' each channel. Having fo'u d sue 1echzt'xtnelyth'e mat-her first oisierateg the pi""oper select?" ma nets:of the switches) an; then op ereste's the hom magnets. It then teis't's'the w tabn 'shezaeonnectio'n enereteases;

In:- previ'ou's: systems when testing. foran 'iiflie channelthe channeltest relays of the are connected with the channel elements overcontactsof a plurality of multicontac-trelays; ThechenneL testrelayshavebattery connected to their windings anct'operete from busyground applied to the channelelements, the. channel corres onding to thefirst non-operated set' ofte's't relty's beingselecte'd'; It will beapfi'aient that, any of the contacts on themiflti'coritact rele ys fans"to close properly; or if" oneo'f the ciicuits is othenmse open, it ispossible to sefect a; channel which includes a htisy element? The testofthe established connection pre'ventSithe use of suchan-erreneouslyselected channel, but requires the reop'eration uf themarket:

In accordance 1 with the present invention-' improved channel: testingmeensis:- provided; 1m eluding means for testing foronewchanneltte'stinereaee- More sp'ecifice' llyl i electronic testingmeans fi plxed with b by means of voltage d'h ider S6- aria the testingmeans' my diet diti'ons' of the testleed-s; namely btisi idE'e 91ndomen.

These and other team-res of be more clearly uh ctrte of the following-(1 rip it) tl'ie di'etwi'ng s in which Fig side" by side Show (Sh-a nettes'tin 1 anti at skelete ed snow-me of the ham'ieTS thecdnneet'in JaysThis cHa-nhe? test suit is 3 espeem'ny" adept: edfoi use a ct'oss e1"dial' System01 the ty tie disclosed in the above-identified patteh}Gnfbefit? reference iem-ade to t afis v fer a complete descript'en ofth'opemtions OM13 bx ieflydescribedhhe' I sated and closesa c-imcliito-vef conductor 2M; beck contact-of relay wt, cdndmter'me tbkthe markerpreference ciiml it 235* of the sereted otfice frame! When" the? nameahiaiflabl'e the preference circuit 2t 5? operates" multieontact re-286* toqconnectthe marker with the eqmpe ment of the office frame; Acircuit then-eluted under the cbntrok of: the di'strizctkfmme: identifiecetiencircuititi for operating themarkenprei erence circuit 21% ofthedistrict-frame?on which iunctor Weiss-located. When the; frameiseva-i lable, the preference circuit: 2&8 climates-5 multi contactreley- 2519." which cen'ne'cts the marker with the equipment: of thedistrict frame.

In the-'meanti me; as described therabcz ve' identified Carpenterpatent; the marker I q'perttte relay" 25 51 which individhel tothwgrdmak' of trunks leading to the? desired oflic'e andsretest? 24%extends" the test. conductors; 2 I 52, em.- ofthese trunks t'o'the-marker whichselectssemidkltnmh Hfianclitheh operates reIeys=21i6.-'-an 2H; Re,

lay 2I1 operates select magnet 2I8 individual to the selected trunk 224,while relay 256 extends the test circuits 2I 9, 220, etc. of the twentytrunk links, which serve the selected trunk, to conductors 239, 240,etc. in the marker for test. Relay 2 I also closes a circuit from groundover a contact of relay 205 to battery through the winding of relay 201to indicate that it has operated.

The marker, through the sender, operates relay 22I in the districtjunctor 200, which extends its operating ground to the winding of relay222. In addition, relay 22I operates select magnet 223, individual todistrict junctor 200. Relay 222 operates and extends its operatingground to the marker over a contact of relay 209 to the winding of relay284, operating that relay to inform the marker that it has operated. Inaddition it extend the test conductors 220, 221, etc. of the twentydistrict links to conductors 236, 231, etc., in the marker for test.With relays 22I, 222 and 209 operated, the outgoing sleeve conductor 225of the district junctor is also extended to the marker. A circuit isalso closed under the joint control of the trunk selecting circuit 203and relay 209 individual to the district frame to operate relay 228which connects the test conductors 229, 230, etc. of the twenty ofiicejunctors forming parts of the channels which may be used to connectdistrict iunctor 200 with trunk 224, to conductors 249, 250, etc. in themarker for test. Relay 228 also closes a circuit from ground over acontact of relay 209 to battery through the winding of relay M0 toindicate to the marker that it has operated. Relay 222 also extends theoperating circuits for the select magnets 23I, 232, etc. individual tothe district links in the district secondary switches, over contacts ofrelay 209 to conductors 25I, 252, etc. in the marker, while relay 2I6extends the operating circuits for select magnets 233, 234, etc.individual to the ofiice links in the oflice primary switches, overcontacts of relay 206 to conductors 253, 254, etc. in the marker.

From the foregoing description it will be apparent that for eachpossible channel, there are five circuits in the .marker, namely, threetest circuits for the three links, which are also used for operating theassociated hold magnets, and two operating circuits for select magnets.

When relays 201, 2 I0 and 284 have operated as an indication that thetest circuits have been extended to the marker, a circuit is closed fromground over the right contacts of relays 284, 2") and 201, conductor 2IIto battery through the winding of relay I02. Relay I02 operates,connecting +130 volt battery to conductor I03.

With +130 volt battery connected to conductor I03, a plurality ofvoltage divider circuits are energized. Each of these circuits extendsfrom -48 volt battery on conductor 286 to +130 volt battery on conductorI03 and is made up of two high resistances. There is a voltage dividerfor each of the three test circuits for twenty channels, that is sixtyin all. Each test circuit is connected to the junction between theresistances of one voltage divider. For example, conductor 231 of themarker which has been connected to test conductor 221 of a district linkis connected to the junction between resistances 241 and 251.

Test conductor 221 is marked with ground through a low resistance whenthe associated district link is busy and with -48 volt battery throughthe low resistance winding of the associated hold magnet when the linkis idle. Re-

sistances 241 and 251, as well as the resistances of the other voltagedividers, are of such magnitude that the potentials on conductor 231 donot appreciably differ from those on conductor 221 when these twoconductors are connected together. However, if because of faulty contactclosure or a break in one of the wires, conductor 221 is not connectedto conductor 231 a potential of +50 volts appears on conductor 231.

Conductors 231, 250 and 240, connected to the test conductors of thethree links making up a channel are connected individually to the inputof rectifiers 261, 210 and 200 the outputs of which are in turnconnected in multiple to conductor 281 and a common rectifier 280.

A similar arrangement is provided for each channel and the outputs ofthe common rectifiers are in turn connected in multiple and throughresistance 282, conductor 2I2, contacts of relays 284, 2I0 and 201,resistance 283 to the control anode of tube 2I3. With this arrangement,the potential on conductor 2 I 2 will be that of the most positive ofthe test conductors. Therefore if all of the test circuits are complete,the potential on conductor 212 will be either 48 volts or zero.

However, if any one of the test circuits is incomplete, the potential onconductor 2I2 will be +50 volts. With +50 volts connected to the controlanode of tube 2I3 and l8 volts connected through relay 235 to thecathode the voltage drop across the control gap is suiiicient to causethe tube to break down, whereupon relay 235 operates across the main gapto +130 volt battery on conductor I03. Relay 235 cause the troubleindicator to make a record, but does not interfere with channelselection.

A channel test tube, such as tube I04 or I05, is provided for each ofthe twenty channels. These tubes are five-element, separate starterscreen grid types, arranged in a lock-out chain with impedances I00 andI01 in the screen and starter anode circuits, respectively. Followingthe operation of relay I02, which takes place, as above described, afterthe test circuit have been closed through to the marker, the screens areconnected through resistance I08 and impedance I06 to the full +130 voltbattery. The starter anodes are connected through impedance I01 to areduced positive potential, about volts, obtained from the volt sourceby means of resistance I00 and voltage regulator tube I I0.

Referring to tube I04, 48 volt battery is normally connected throughhigh resistance III to the starter cathode of tube I04. Conductor 281,to which the test conductors of this channel are connected, is alsoconnected through resistance II2 to the starter cathode of tube I04. Apreviously described, if all of the test circuits are complete andconnected to idle links, the potential on conductor 281 will beapproximately 48 volts If any link is busy, ground potential appears onconductor 281 and if any test circuit is open +50 volts appear on thatconductor. With either ground or +50 volts on conductor 281, theresulting potential on the starter cathode will be such that, whenpotential is applied to the starter anode, no breakdown will take place.With -48 volts on conductor 281, the starter anode-starter cathode gapwill break down, followed in turn by a breakdown of the screen andstarter cathode gap and breakdown of the main cathode-main anode gap.

Only one of the channel test tubes I04, I05, etc. will operate as thereduction of screen voltagein the operated? tube renders; the: transimpossible other tubes.

Assuming thatrtuh'ez EM istheonsetoi operate; relay lite, included themama gap circuit, op:-= crates; Relay twmayconveniently baaimercurycontact relay. As. soonasreiay |E|I3 operates, it: connectsgroundtoacomiuctors 252i and 215kfoper' ating select magnets: 232* andi 2341to. prepare: the? cross-points of the district. secondary and; emceeprimary switches;

The operation: ofi'rel'ay H31 disconneots grounct from: in shunt ofcondenser" H5! and that: con denser starts to charge through resistancel l 'fif from: +-130 volt battery on conductor me Com denser ore isconnectedfi throughresistances no: to the: control-' electrode oi: tubeM82 and after. an interval} determined; by: the values of resist-e anceHi6 and-condenser H 5; theipotentiai omcond'enser- H 5 rises to"v a;sufiicient value; tubes M8 breaks: down: andi relay H59: operates: overthe: main! gap of tube: M8 to -PIF'0 volt hatter-3 on conductor H13.

Relay H9: extends the: links of the selected chamael to the hold magnet:operating f circuits; Condenser l zfl has been previously charged from:hattery'onoon'd uctor W3 through resistance- F2 1 and the winding ofrelay I22. When relay I- Hi operates; it: connects ground over itscon-tact! t'o condenser m1 iii-shunt: of resistance m andcondenser: 20discharges relay I22 operating the.- disoharge currentz- Whilerelay F22isoperated; it connects +130 volt battery: from: conductor H13 overitscontactandi contacts 4 of relay H 9; conductor 2420 and over contactsof relays" 266 and: 21-6 to -48 volt battery throughthe-winding of'holdmagnet 230' of the secondary oflice switch Magnet 29 il c1'oses thecross-point 218 prepared by select: magnet 2 ft; thereby connectingground to conductor 215 tomark the husyto other-- markers. When relay2|! operated as previouslydescriheci} it connected +13o1voIt: batterythrough resistance 2 1 6 to condoctor: 21-1. 'lihereiore with crosspoint 2%8 closed; magnetare" helit operatedunder theoontrol of relay-2H.

Relay: H 9 also connects groundi over itscontact! to cond'enser' I23;causingthat condensertocharge-throughthewindirig of relay I 24 from"+l8fi volt battery on conductor W3; Relay IZW operates from" thischarging current and closes a circuit from +1'3-0-vo1 t batter-yonconductor -03; resistance" I 25; contact of relay I24; contact 3':-ofrelay l fe; conductor 25!) over contacts t relays; 209 and 228* to--48 volt battery through the-windings of hold -magnets' 2'9 and 292'.Mag met: 29?: closes crosspoint 2 prepared by select magnet i34extending the +130--volt-Joattery-' sup plied by relay 2M to conductor 230' to hold" both magnets; 292* and 29h operated.- Magnet' 2 M closescross-point 2'93" prepared by select mag net? 232, extending +130 voltbattery to QUIT doctor 221-, operating: hold magnet 285 which: closescross point' Z95; and connects conductor 221 toaconduetor 2 with.rel'ay- H 9 operated 1=301vo1t= battery oncon'du'ct'on 22 1:: is:connected over contacts-of roe laysazflxand zoo, conductor 237;. contact5% oi re"- ue tov condenser: 128*.. condenser: I228; which is: connectedtozthecontrolcatho'deofi tube I29;

char es inxthisicimuit and when thetronietuhe-device also'connectedwith'saidchancondenser l m'reaoheszthet break-down potential,

tube k291i hreal'ss dew n1 and relay tha operates. Relay I connects:+1302 volt battery on. con (motor? through; resistancel'3'l to:-comiensei 325. the condenser to charge? a cross-point; zasiie closeatthei lineisconnected:throughto theztrunk;causing the operation of relay29% which connectsgroim'd to conductor 21 1*. Conductor 21 1 isconnected through cross-point; 2H8; conductor 22M.- cross-- point 2943..conductor" 230, cross -pomt 293, com ductor ZtT, cross-point 295conductor 2%, taets at relays: 2213, 222 ands 20%. connector: 291%;contact: 2' or relay IZIIE to:- condenser. 932; causing? thatcondenserrto discharges condenser? 1532' is cnnnle'oteztto the" controllcathod e of tube I231 Which'iS so that: the: negative surge pros ducedby: th discharge: of. condenser 1532 tuhetto break. down ancL-operate:re1ay: H30! Relax" mo; operateriopensrtheecircuit over-whichthe: ofiice frame: marker preference circuit open ated; thereby:releasingz'the:ofiice frame conneoton oiitcuitslfol'l'owert by thedistrictl-fsaime connector circuits;

The: release on the? districts frame-- connector circuitsreleases: relayZ2115,-v extending conducts 225 to the: sleeve on the district junctorto: holii-i that circuit,

With the :frameiconnector 'circuitsreleaseci}. re lays 284, 2 HI:andl'fi I'rel'e'ase, in turn releasing-we lay= I112: to; remove volt:battery f1-'-O1-I-YCOH-T- doctor lilltandtrestore thesehanneltestingohcui'th tonomnah The further operation of: the marker-' takes:place: as described: in a the above-mentioned patent;

If ire1ay 2-35 has been operated because one of? the. channei testcircuits was open; a trouble ca'tor record will he made before the.marker can: releasei While the foregoing description is directed to theestablishment of the outgoing stage ofia call; it will be apparent thata similar arrangement" wouldhe equally'applicab'le'to theincoming stage.

What is claimed"? is? 1. In. a telephone system, incoming. circuits,outgoing circuits, a plurality of channels each comprising a pluralityof sections for connecting an' incoming circuit? and an outgoingvcircuit, a test conductor. for each of saidf channel sections normallymarked with negative. battery. 'or. grounci according as said section,is idle on busy, and. means to simultaneously test the sections or, achannel for an idle condition, a; busy condition or an open condition onany one ofi'sai'djsections including a circuit network for supplyingaposil tive potential to each. of said; testi condiictors-,, said"positive potential being neutralized: by. the negative battery or groundon. the connectecf channel section, van asymmetric conductinggrdevice.individ'ual'to' each of s'ai'd" test conductors, a-channel' testconductor; a negative potential connected'l to saidchannel testconductor; the testcondiuctors of one channel Being connected. inmultiple; through said" individual asymmetric conducting. d'evices't'osai'dichanneltest conductor, said asymL- metric conducting devices beingpoled to. pass; the more positive potentials to saicl'channeftestconductor wherebythe'neg'ative' potentiall'on. saiii; channel testconductor is counteractedifany. one of saicl'test conductors 'islb'usy.or open,,,a. channel selecting, electronic tfuhe device connected with;saidlohann'el test conductor and'responsive to. the presence of saidnegative potential on. said chantnel test'conductor; and a troubleindicating elecnel test-'conduetor-andresponsive-to-the presence onpositive potential on saiii channel testcon duct'or'diie'to antopentesticonduoton 2. In: a: telephone system; incoming 7:5 outgoing;circuits a plurality 0t channels comprising a plurality of sections forconnecting an incoming circuit and an outgoing circuit, a test conductorfor each of said channel sections normally marked with negative batteryor ground according as said section is idle or busy, testing means foreach of said channels for testing said channels simultaneously, each ofsaid testing means including means to simultaneously test the sectionsof a channel for an idle condition, a busy condition or an opencondition on any one of said sections, including a circuit network forsupplying a positive potential to each of said test conductors, saidpositive potential being neutralized by the negative battery or groundon the connected channel section, an asymmetric conducting deviceindividual to each of said test conductors, a channel test conductor foreach channel, a negative potential connected to each of said channeltest conductors, the test conductors of the sections of one channelbeing connected in multiple through their individual asymmetricconducting devices to said channel test conductor, said asymmetricconducting devices being poled to pass the more positive potentials tosaid channel test conductor, whereby the negative potential on saidchannel test conductor is counteracted if any one of said testconductors is busy or open, a channel selecting electronic tube deviceconnected with each of said channel test conductors and responsive tothe presence of said negative potential on said channel test conductor,circuits interconnecting said channel selecting electronic tube devicesto permit only one responsive tube to operate, an auxiliary asymmetricconducting device connected to each of said channel test conductors andpoled to pass positive potential, and a trouble indicating electronictube device connected to all of said channel test conductors throughsaid auxiliary asymmetric conducting devices and responsive to thepresence of 2+- positive potential on any one of said channel testconductors due to an open test conductor.

3. In a telephone system, incoming circuits, outgoing circuits, aplurality of channels each comprising a plurality of sections forconnecting an incoming circuit and an outgoing circuit, a test conductorfor each of said channel sections normally marked with negative batteryor ground according as said section is idle or busy, a common testingdevice, means for connecting said channel sections with said testingdevice, said device including testing means for each of said channelsfor testing said channels simultaneously, each of said testing meansincluding a circuit network for supplying a positive potential to eachof said test conductors, said positive potential being neutralized bythe negative battery or ground on the connected channel section, anasymmetric conducting device individual to each of said test conductors,a channel test conductor for each channel, a negative potentialconnected to said channel test conductor, the test conductors of thesections of one channel being connected in multiple through theirindividual asymmetric conducting devices to said channel test conductor,said asymmetric conducting devices being poled to pass the more positivepotentials to said channel test conductor, whereby the negativepotential on said channel test conductor is counteracted if any one ofsaid test conductors is busy or open, a channel selecting gas-filledtube connected with each of said channel test conductors and responsiveto the presence of said negative potential on said channel testconductor, an auxiliary a ymmetric conducting device connected to eachof said channel test conductors and poled to pass positive potential, atrouble indicating gas-filled tube connected to all of said channel testconductors through said auxiliary asymmetric conducting devices andresponsive to the presence of positive potential on any one of saidchannel test conductors due to an open test conductor, means operated asa result of the connection of said channel sections with said testingdevice to render said gas-filled tubes responsive, means for preventingmore than one of said operative channel testing tubes from operating,and means under the control of an oper-.

ated channel testing tube to connect said sections to establish aconnection between an incoming circuit and an outgoing circuit includingsaid selected channel and to release said testing means.

4. In a telephone system, incoming circuits, outgoing circuits, aplurality of channels each comprising a plurality of sections forconnecting an incoming circuit and an outgoing circuit, a test conductorfor each of said channel sections normally marked with negative batteryor ground according as said section is idle or busy, a common testingdevice, means for connecting said channel sections with said testingdevice, said device including testing means for each of said channelsfor testing said channels simultaneously for an idle channel, and meansfor testing all of said sections for an open section or test conductorincluding a circuit network for supplying a positive potential to eachof said test conductors, said positive potential being neutralized bythe negative battery or ground on the connected channel section, anasymmetric conducting device individual to each test conductor, saidasymmetric conducting devices being poled to pass the more positivepotentials to said channel test conductor,

a trouble indicating gas-filled tube connected to all or said channeltest conductors through said asymmetric conducting devices andresponsive to the presence of positive potential on any one of said testconductors, and means under the control of said trouble indicating tubeto cause a trouble indicating record to be made.

5. In a telephone system, incoming circuits, outgoing circuits, aplurality of channels each comprising a plurality of sections forconnecting an incoming circuit and an outgoing circuit, a test conductorfor each of said channel sections normally marked with negative batteryor ground according as said section is idle or busy, a common testingdevice, means for connecting said channel sections with said testingdevice, said device including testing means for each of said channelsfor testing said channels simultaneously for an idle channel, and meansfor testing all of said sections for an open section or test conductorincluding a circuit network for supplying a positive potential to eachof said test conductors, said positive potential being neutralized bythe negative battery or ground on the connected channel section, anasymmetric conducting device individual to each test conductor, achannel test conductor for each channel, the test conductors of thesections of one channel being connected in multiple through theirindividual asymmetric conducting devices to said channel test conductor,said asymmetric conducting devices being poled to pass positivepotentials to said channel test conductor, an auxiliary asymmetricconducting device connected to each of said channel test conductors andpoled to pass positive potential, a trouble indicating gas-filled tubeconnected to all of said channel test conductors through said ReferencesCited in the file of this patent UNITED STATES PATENTS Name Date ClarkDec. 1, 1925 Number Number 10 Name Date Buchanan et a1. Feb. 25, 1941Carpenter Mar. 18, 1941 Holden Oct. 2'7, 1942 Scheer Oct. 19, 1943Horwitz Dec. 13, 1949 Bray et a1 Apr. 4, 1950 Germanton Jan. 1, 1952Bruce et a1 Jan. 22, 1952

